1. Field of the Invention
The present invention relates to a fibrous structure having a roughened surface and to a process for producing the same. Upon dyeing, the fibrous structure is greatly improved in color depth. In addition, it gives one a more scrooping feeling than silk does.
2. Description of the Prior Art
A variety of processes have been proposed for improving the color depth and hand of fabrics. So far, no satisfactory technology has been developed which can be applied to all kinds of fibers and produce satisfactory color, hand, and function without the loss of performance.
Natural fibers characteristicly exhibit good moisture absorption but poor dimensional and form stability. Moreover, such fibers are poor in color when dyed as compared with natural brilliant colors of flowers and insects. On the other hand, organic synthetic fibers, especially those which are made by melt spinning, disadvantageously exhibit a peculiar waxy feeling and gloss which comes from the excessive smoothness of the fiber surface and also exhibit poor color development upon dyeing. In addition, such fibers generate static charge and are somewhat inferior in hand to natural fibers.
The above-mentioned disadvantages are usually attributable to the nature of the surface of the fiber. Therefore, efforts have been made to overcome such disadvantages by roughening the fiber surface, without changing the fundamental properties of the fiber, by using fine particles and low-temperature plasma treatment.
It is believed that the luster can be improved and the hand changed by roughening the surface of fibers. Based on this belief, it is common practice to deluster fibers by adding fine particles such as titanium oxide to fibers. However, it is known that while such a process delusters the fabric, it detracts from the color of the fabric. Color, particularly color depth and brilliance, are important requirements for fibers, no matter where the fibers are used.
Although polyester fibers are in general use because of their outstanding properties, they are still plagued by unsolved problems concerning color development. There is a strong demand for polyesters which are superior in color depth and brilliance.
In order to solve these problems, several techniques have been proposed.
The present inventors had previously disclosed in U.S. Pat. No. 4,254,182 and British Pat. No. 2,016,364 a technique for producing a color deepening effect by etching the surface of polyester fibers containing minute inorganic particles with an alkali so that irregularities are formed on the fiber surface.
According to Japanese Pat. Laid-open No. 99400/1977, a color deepening effect is produced by treating an organic synthetic fiber with glow discharge plasma so that irregularities are formed on the fiber surface.
Although the processes disclosed in U.S. Pat. No. 4,254,182 and U.K. No. 2,016,364 can produce a superior color deepening effect which previously had never been achieved with conventional polyester fibers, such processes still have the disadvantage that the resulting polyester decreases in luster; in other words, it is difficult to produce the color deepening effect without the loss of luster. Moreover, it cannot be easily applied to blended fabrics.
On the other hand, the methods described in said Japanese patent also leave some problems yet to be solved. The plasma treatment for ordinary synthetic fibers, or synthetic fibers containing no fine particles, improves the color development performance to a certain extent, which is not wholly satisfactory. Moreover, the plasma treatment is economically disadvantageous because it takes a long time to perform.
There is also known other techniques for producing the color deepening effect by coating the fiber surface with a fluoropolymer or silicone polymer or by forming a thin layer of graft polymer on the fiber surface. However, such techniques suffer from a disadvantage that the polymer formed on the fiber surface impairs the hand of the fabric and causes poor adhesion to interlinings due to its inherently slippery properties and the coloring effect is limited.